It's impossible to know exactly what your tax rate will be during retirement, especially if it's more than a decade out. You can try to guess though.
You can expect that your income will be based on how much you will spend during a year in retirement. Make a guess as to how much that would be in current dollars. Let's say $40k for the sake of argument.
Where will your money be coming from? You already have Roth retirement accounts and a taxable brokerage account. Looks like your investments are about 50% Roth, 40% taxable, and 10% cash. Let's assume you maintain this ratio until retirement, and withdraw from each account in equal proportions each year.
That would mean, in this example, you would be withdrawing $20k from your Roth accounts, $16k from your taxable accounts, and $4k from cash. Your Roth withdrawals won't count as income. Your taxable account withdrawals only count as income to the extent that you had capital gains, and the cash wouldn't be taxed either. Even if your taxable shares quadrupled in value since you bought them, that would only be $12k of capital gains income and no regular income. You would also have some dividend income from the taxable account. Even then, it sounds like your tax rate would be pretty low!
What if you started contributing much more to traditional retirement accounts, and this changed your ratio at retirement to 40% traditional, 20% Roth, 40% taxable? Then you would be withdrawing $16k from traditional, $16k from taxable, and $8k from Roth. The $16k of income from your traditional retirement accounts would cover the standard deduction and personal exemption for a single person, and the remainder would be taxed at 10% under the current system. The taxable withdrawals and dividends would have the same income as before, and Roth would still provide no income.
This seems like it would likely be a win compared to your current path, where you're paying 25% (or maybe even 28%) to put money in a Roth account and are not projecting any "regular" (non-dividend/capital gain) income during retirement. Tax rates could go up quite a bit between now and then and you would still come out ahead by having some money in traditional retirement accounts.